A primary headache disorder that is characterized by severe, strictly unilateral pain which is orbital, supraorbital, temporal or in any combination of these sites, lasting 15-180 min. Occurring 1 to 8 times a day. The attacks are associated with one or more of the following, all of which are ipsilateral: conjunctival injection, lacrimation, nasal congestion, rhinorrhea, facial sweating, eyelid edema, and miosis. (international classification of headache disorders, 2nd ed. Cephalalgia 2004: suppl 1)